Resistor switch synchronizing operating mechanism

ABSTRACT

An operating mechanism comprising interacting linkage arranged to effect the closing of a resistor contact prior to the closing of a main contact and thereafter withdrawing the resistor contact. Operation of a blast valve is synchronism with the opening of the main contact to provide a blast of fluid under pressure to the arcing area is also accomplished.

United States Patent Benham Nov. 25, 1975 [54] RESISTOR SWITCH SYNCHRONIZING 3,291,947 12/1966 Van Sickle 200/144 AP OPERATING MECHANSM' 3,482,069 12/1969 Badey et a1... 200/144 AP 3,676,621 7/1972 Pflanz 200/144 AP [75] Invent r: G rge K- Benham, s r 3,763,340 10/1973 Noack u 200/144 AP Mass. 3,852,548 12/1974 Goodwin, Jr 200/148 F [73] Assignee: Allis-Chalmers Corporation,

Mnwaukee, wi Primary Examiner-Robert S. Macon [22] F1 d F h :9 1974 Attorney, Agent, or Firm-Robert C. Jones [21] Appl. No.: 443,919 [57] ABSTRACT An operating mechanism comprising interacting link- 200,148 200/148 1652 52 age arranged to effect the closing of a resistor contact AP l48/R prior to the ciosing of a main contact and thereafter 1 o are 6 M8 withdrawing the resistor contact Operation of a blast I va1ve is synchronism with the opening of the main Re'erences Cited contact to provide a blast of fluid under pressure to the arcing area is also accomplished.

12 Claims, 7 Drawing Figures U. S. Patent Nov. 25, 1975 Sheet 1 of 3 3,922,512

US. Patent Nov. 25, 1975 Sheet 2 of3 3,922,512

US. Patent Nov. 25, 1975 Sheet 3 of3 3,922,512

RESISTOR SWITCH SYNCI-IRONIZING OPERATING MECHANISM BACKGROUND OF THE INVENTION This invention relates generally to circuit breakers and more particularly to the operating mechanism for operating the main contacts and associated resistor contacts in synchronism with provision being made to actuate a blast valve. In previous circuit breaker arrangements it has been the practice to use separate resistor units externally of the housing in which the main contacts are located. This arrangement necessitates separate operating devices for the contacts of each unit. As a result, the separate operating devices require complicated arrangements for synchronizing the movement of the resistor contacts with the movement of the main contacts. Also, a dual operating arrangement makes it extremely difficult to provide both the resistor contacts and the main contacts with gas insulation. This is true because the complicated sealing arrangement that is necessary for the dual individual mechanical operators is impractical and extremely costly. Indeed, to avoid the dual individual mechanical operators, fluid amplifier arrangements have been provided to avoid individual mechanical operators as exemplified in US. Pat. No. 3,660,625.

SUMMARY OF THE INVENTION As will hereinafter appear, the invention enables simple and reliable means to be employed for operating main and auxiliary contacts of a gas insulated circuit breaker to be operated in synchronism. Also, the invention makes it possible to provide a compact operating arrangement capable of being included within the gas insulated housing so that no gas sealing problems are experienced.

A compact arrangement of the main contacts and the auxiliary contacts in physical parallel relationship is feasible, thus reducing the size of the sealed housing in which the contacts are enclosed.

In accordance with the preferred embodiment of the invention, there is provided an operating mechanism for effecting the closing and opening movement of a resistor contact in synchronism with closing movement of the main contact of a circuit breaker. Included in the arrangement is the provision of means for actuating an associated blast valve. The closing movement of the resistor contact is effected prior to the closing of the circuit breaker contact. Thereafter, the resistor contact is moved to open position. In a circuit breaker main contact opening operation. the main circuit breaker contact is moved to open position in synchronism with the opening movement of a blast valve to provide a blast of fluid under pressure to the arcing area.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged fragmentary view of a gas insulated circuit breaker with parts broken away to show the operating mechanism therein for opening and closing the circuit breaker contacts and the resistor contact, the showing being made with the operating mechanism in the condition after effecting the closing of the circuit breaker contact and after the resistor contact is returned to an open position;

FIG. 2 is an enlarged detail view of the operating mechanism of FIG. 1 showing the position of the oper- 2 ating mechanism with the circuit breaker contact and resistor contact both in open positions;

FIG. 3 is a detail view of the two breaker links taken along line IIlllI of FIG. 2; and,

FIGS. 4 through 7 are schematic views of the operating mechanism of FIGS. 1 and 2 showing the various positions of the components in a complete cycle of operation.

DESCRIPTION OF THE INVENTION Referring to the drawings and more particularly to FIG. 1 thereof, there is shown an enclosed gas insulated circuit breaker or interrupter l0 incorporating the teaching of the invention. The circuit breaker I0 is enclosed in a gas tight enclosure tank II. Within the tank 11 there is supported a central housing 16 which is operatively supported in depending relationship from a central insulating tube 17 that is secured to an upper mounting flange bracket (not shown). The central housing 16 is metallic and serves both as a support and as a conductor for a pair of serially connected contact and blast valve units 18, one of which is shown.

The contact and blast valve units 18 are identical; and, thus, a description of the unit 18 will also apply to the opposite unit. As shown, the contact in blast valve unit 18 comprises an insulating contact housing 21 which is supported by a mounting frame 22 that is bolted in electrical conducting relationship to the central housing 16. As viewed in FIG. 1, the leftward extending end (not shown) of the housing 21 includes a mounting plate (not shown) to which a rightwardly axially extending tubular stationary contact 23 is secured. The rightwardly extending end of the contact 23 is hollow so that it will serve as an exhaust nozzle and is provided with a plurality of spring biased radially disposed contact fingers adapted to receive the end of an axially movable main contact 26. The axially movable main contact 26 is supported for axial movement in a tubular supporting nozzle 27 which is integrally formed as a part of the supporting frame 22. Surrounding the supporting nozzle 27 is a circular gas passage 28 which has communication with a circular gas passage 29 formed in the supporting frame 22. The supporting frame 22 has an angularly, downwardly extending portion 31 in which a U-shaped gas passage 32 is formed and which communicates with the circular passage 29.

An elbow member 33 is secured to the bottom mounting surface 34 of the frame 22. The opposite end of the elbow 33 mates in sealed relationship on an outlet of a T-shaped header 37 which operates to distribute high pressure gas to the leftwardly extending unit 18 and to a complementary rightwardly extending unit (not shown).

With the elbow 33 there is operatively supported a blast valve 38 which is biased to closed position by means of a compression spring 39. The blast valve 38 is adapted to be moved axially downwardly to allow a blast of high pressure gas to flow from the elbow into the passage 32 and 29, and, thus, to the passage 28 to be directed thereby to the arcing area 42 to extinguish the are established between the movable contact 26 and stationary contact 23 upon the opening movement of the contact 26.

Gas at a relatively high pressure is supplied to the elbow 33 through the distribution header 37 via an insulating supply tube 43 which engages within a flange 44 of the header 37. A supply of gas is available to the supply tube 43 from a high pressure tank (not shown) that is in communication with the lower end of the supply tube 43 and which is supported by the housing 11.

The movable contact 26 is moved to an open position in synchronisrn with the opening of the blast valve 38. Thus, before the contact 26 is moved to a position where it is just about to separate from the stationary contact 23, the blast valve 38 is opened to allow a blast of high pressure gas to flow to the area 42 so that the high pressure gas is available at the instant the movable contact 26 separates from the stationary contact 23 and draws an arc so that the gas can extinguish the arc.

The gas insulated circuit breaker includes a resistance switch 55 for insertion into and out of the circuit in synchronism with the closing of the circuit breaker contact 26. As depicted in FIG. 1, the resistance switch 55 is enclosed within an insulating housing 56 that is supported by the mounting frame 22 which also supports the circuit breaker insulated housing 21. As viewed in FIG. 1, the leftwardly extending end (not shown) of the insulating housing 56 is adapted to sup port a rightwardly extending stationary tubular resistor contact 57 and the associated corona shield 58. The tubular stationary contact 57 is adapted to receive the end of an axially movable contact 59. To this end, the movable contact 59 is supported in coaxial relationship in a movable guide piston 62 which is disposed within a hollow cylindrical guide 63. The cylindrical guide 63, in turn, is secured to the mounting frame 22. Mounted on the extending end of the cylindrical guide 63 is a corona shield 64.

A compression spring 66 is disposed within the cylindrical guide and arranged in abutting engagement with an inwardly extending radial flange formed on the left end of the guide 63. The opposite end of the spring 66 abuts the leftwardly facing surface of the piston 62. Thus, the spring 66 operates to normally urge the piston 62 rightwardly, as viewed in FIGS. 1 and 2, to maintain the piston and thereby the contact in an open position.

Axial movement of the circuit breaker main contact 26 to open and closed positions relative to the stationary contact 23 is effected by an operator mechanism 70 which is actuated by means of the movable operating rod 51. Axial movement of the movable contact 26 is accomplished by means of a connecting rod 65 that is pivotally connected to the end of the movable contact 26. The opposite end of the connecting rod 65 is pivotally connected to an arm 67 of a drive crank 68 that is mounted for arcuate movement about a pin 69. The drive crank 68 has integrally formed therewith a relatively short arm 71, the free end of which is pivotally connected to the end of an adjustable tying link 72. As shown, the tie link 72 is pivotally attached to a guide piston 73 carried by the insulated actuating rod 51. Thus, upward movement of the piston 73, as viewed in FIG. 1, will effect the upward movement of the tie link 72, thereby pivoting the arcuate crank 68 about the pin 69 in a clockwise direction. The clockwise pivotal movement of the crank 68, as described, will effect withdrawal or opening of the contact 26.

As previously mentioned, the operator 70 also effects the synchronous operation of the resistor contact 59 in relationship to the closing movement of the circuit breaker contact 26. To effect the movement of the resistor contact 59, there is provided an adjustable connecting rod 76 that has one end pivotally connected to an axially extending boss 77 formed on the rightwardly facing surface of the piston 62. The opposite end of the connecting rod 76 is pivotally connected as at 78 to one corner ofa triangular configured bell crank 80. The fulcrum point of the bell crank 80 is pivotally connected, as at 81, to a fixed abutment 82 which extends upwardly from the mounting frame 22. Thus, as the bell crank 80 is moved in a counterclockwise direction about the pivot point 81, as viewed in FIGS. 1 and 2, the guide piston 62 and, thus, the resistor contact 59 will be caused to move leftwardly to a contact closed position.

To effect the pivotal movement of the bell crank 80 in a clockwise or counterclockwise direction, there is provided an operative connection to the operator crank 68. To this end, a two-part toggle link 86 is oper atively interconnected between the bell crank 80 and a dog-leg configured toggle crank 87. The two-part toggle link 86 comprises a first link 88 having one end pivotally connected to the third corner of the bell crank 80, as at 89. The opposite end of the first link 88 is pivotally connected to a second link 91, as at 92. The arrangement is such that the connecting end of the second link 91 is bifurcated and receives the end of the first link 88 between its bifurcated portions with the pivot pin 92 effecting the pivotal connection therebe tween. The opposite end of the second link 91 is pivotally connected to the adjacent end 93 of the toggle crank 87, as at 94. To establish a rigid in-line connection between the first and second links 88 and 91, the end of the first link 88, which is disposed between the bifurcated end of the second link 91, is constructed with a hook or abutment portion 96 that is constructed and arranged in a manner to extend above the top surface 97 of the second link 91. As shown in FIG. 2, the top surface 97 of the second link 91 is relieved to form semicircular hub ends 98 and 99. Since the hub end 98 of the link 91 is bifurcated, each of the legs of the bifurcated end presents semicircular hub portions 98A and 98B, FIG. 3.

A nose 100 of the hook 96 engages the top surface 97 of the second link 91 and thus serves as a cantilever brace to unite the first and second links 88 and 91 into a single rigid substantially in-line connecting link which is breakable or releasable.

The construction and arrangement of the first and second links 88 and 91 are such that the center X of the pivot 92 is slightly below or to the left of a line Y-Y that passes through the center of the pivots 89 and 94 as viewed in FIG. 2. Thus, with the two links 88 and 91 in slightly over-centered in-line position, as described, the nose portion 100 of the hook 96 forcefully bears on the surface 97 of the second link to make a strong, rigid, force transmitting connection between the bell crank 80 and the toggle crank 87.

To increase the stiffness of the joint at the pivot 92 and thereby increase the rigidity of the breakable twopart toggle link 86 and to insure retention of the links 88 and 91 in a substantially in-line over-centered position, a bias is applied to the joint 92 by means of a flat spring 101. As shown, the flat spring 101 is disposed on the top surface 102 of the first link 88 and is maintained in position by screws 103. The free end of the flat spring 101 extends towards the hook end 96 and forcefully engages the surfaces of the hubs 98A and 988. Thus, the force of the leaf spring 101 tends to force the pivot joint 92 downwardly, as viewed in FIG. 2, to yieldably retain the center X below the line Y-Y.

The toggle crank 87 is supported for pivotal movement on a boss 108 formed on the mounting frame 22,

being secured thereto by a pivot pin 109.

To transmit movement to the toggle crank 87, an ad justable tie link 111 is pivotally connected to the pin 94 and has its opposite end pivotally connected to the outer end of the arm 67 as at 112. Thus, as the crank 68 is operated to move its arm 67 in a counterclockwise direction, as viewed in FIG. 2, the toggle crank will pivot about pin 109 so that the center of the pivot pin 94 will move in an arcuate path of travel in a counterclockwise direction. As a result of the arcuate travel of the end of the pivot pin 94, the toggle link 86 as a unit will be caused to move angularly upwardly. The upward movement of the toggle link 86 will effect pivotal movement of the bell crank 80 about the pivot pin 81 which, in turn, operates the resistor contact 59.

As previously mentioned, the operator 70 also effects the synchronous operation of the blast valve 38 in timed relationship to the opening movement of the main contact 26. To effect the timed opening movement of the blast valve 38, the hub of the arm 68 is formed with a cam portion 121. Thus, as the arm 68 is moved in a clockwise direction, as viewed in FIG. 1, the cam portion 121 will move with it in the same direction. As the cam portion 121 moves in a clockwise direction, a vertical cam face 122 formed on the cam portion 121 engages against a tongue portion 123 of a latch 124. The tongue portion 123 is supported for axial movement in a bore 126 and is urged outwardly thereof by means of a spring 127. The spring 127 is retained in position by means of a threaded nut 128. The latch 124 is provided with two vertically extending spaced apart arms 129, one of which is shown, which are pivotally mounted on the pin 69. Thus, as the cam portion 121 turns in a clockwise direction, the vertical cam face 122 will engage the side of the latch tongue 123 thereby forcing the latch 124 to pivot about the pin 69 in a clockwise direction. The pivotal movement of the latch 124 in a clockwise direction, as viewed in FIG. 1, will effect the opening of the blast valve 38. To this end, the latch 124 is provided with a bifurcated arm portion 132 which receives the lower end of an adjustable rod 133 therebetween.

A pin 134 operates to pivotally connect the rod 133 between the bifurcated arm 132 to allow the rod to have freedom of movement in a vertical plane. The upper end of the rod 133 is pivotally connected to the rightwardly extending end of an arm ofa rocker arm or lever 135 that is pivotally mounted on the pin 109 on which the toggle crank 87 is also pivotally supported. The leftwardly extending end of the rocker arm 135, as viewed in FIGS. 1 and 2, is pivotally connected to a blast valve actuating rod 136. As shown, the rod 136 extends through a suitable opening in the bottom portion of the frame 22. The rod 136 is adapted to engage the blast valve 38 when the rocker arm 135 is pivoted in a counterclockwise direction, as viewed in FIGS. 1 and 2. Counterclockwise pivotal movement of the rocker arm 135 about the pin 109 is effected by the pivotal movement of the latch body 124 in a clockwise direction. The clockwise pivotal movement of the latch body 124 imparts an upward movement to the rod 133, thereby effecting the pivotal movement of the rocker arm 135 about pin 109. This movement of the rocker arm 135 will cause the rod 136 to move downwardly and to engage and open the blast valve 38 allowing gas at a relatively high pressure to flow to the arcing area 42.

As previously mentioned, the blast valve 38 must be allowed to close after a blast of gas has been delivered to the arcing area 42 and prior to the complete movement of the movable contact 26 to its full open position. To effect a release of the blast valve 38 while still maintaining the rightward withdrawal movement of the contact 26, a disengaging means is provided which is operative to release the latch body 124 from the operating linkage. To this end, as the latch body 124 moves in a clockwise direction, as viewed in FIG. 1, the tongue portion 123 thereof abuts a cam surface 137 until such time as the corner 138 of the tongue portion 123 of the latch 124 engages horizontal flat surfaces 139 formed on a pair of spaced apart stationary cam members, one of which is shown in FIGS. 1 and 2. Stationary cam members 141 are mounted on the pin 69 and have downwardly extending angularly inclined arm portions 142. The arm portions 142 are held stationary by means of a transversely extending pin 143 that is engaged in a vertical groove 144 formed in a fixed abutment 147. Thus, as the corner 138 of the tongue 123 of the latch 124 engages against the stationary cam surface 139 of the stationary cam member 141, the arms 142 by operation of the pin 143 restrain the fixed cams 141 from rotating. Thus, as the cam member 121 is continued in its rotary motion about the pin 69 in a clockwise direction, the latch body 124 moving with the cam 121 will forcefully engage the corner portion 138 of the tongue 123 against the surface 139, thereby forcing the latch tongue 123 inwardly against the pres sure of the spring 127. As the rotation of the latch body 124 continues in a clockwise direction, the latch tongue 123 will be moved inwardly further into the bore 126 until such time as a trailing cam surface 148 moves over the top surface of the tongue portion 123 of the latch so that the tongue 123 rides on the surface 148. With this condition obtained, a tension spring 149, FIGS. 1 and 2, urges the rocker arm to pivot about the pin 109 in a clockwise direction, thereby lifting the rod 136 free of the blast valve 38 to release the blast valve so that a spring 39 will return the valve 38 to its closed position. This condition is obtained because the tongue 123 now rides on the cam surface 148 and, thus, under the urgency of the spring 149, the latch body 124 will return to its original position, depicted in FIG. 1. Thus, as the cam member 121 continues to rotate in a clockwise direction to effect the complete opening movement of the movable contact 26 rightwardly, the blast valve 38 will be free to reset to closed position for subsequent operation.

In operation, assuming that the movable main switch contact 26 is in full closed position and that the movable resistor contact 59 is in full open position and also that the blast valve 38 is closed, under these conditions the linkage mechanism will be in the position depicted in FIG. 1 and schematically in FIG. 7. To effect an opening operation of the circuit breaker contact 26, the rod 51 will be moved upwardly to initiate the opening operation. Upward movement of the rod 51 will effect an angular upward movement of the adjustable tie link 72. This movement effects clockwise rotation of the short arm 71 of crank 68. As a result, the long arm 67 of the crank 68 also rotates in a clockwise direction thereby moving the crank 87 and the joint 94 in a clockwise direction of rotation, as viewed in FIGS. 1 and 7. The arcuate movement of the pivot joint 94 causes rightwardly movement of the links 88 and 91 and joint 92; the link 88 pivoting about the pin 89.

After the pivot joint 94 passes the apex in its arcuate path of travel, further travel causes the links 88 and 91 and the joint 92 to move leftwardly and downwardly, bringing them substantially into their in-line position. Thus, the force components on the broken joint 92 of the two part toggle link 86 will be such as to effect the movement of the link 91 into an in-line position with the link 88. As the movement of the arm 67 of crank 68 continues in a rightwardly direction, a tension spring 153, connected between the abutment 82 and the link 88, operates to exert a force on the two-part toggle link 86 to pull the toggle joint 92 back to a reset" or overcenter position as indicated in the schematic representation in FIG. 4. As this condition obtains, the movable main contact 26 will have separated to open circuit position.

As previously mentioned, as the movable main contact 26 is separated from its associated stationary contact 23, an arc is drawn therebetween on the arcing area 42. At this time a blast of fluid under pressure is provided at the arcing area 42 by the opening of the blast valve 38. To this end, as the crank 68 is moved in a clockwise direction, as viewed in FIG. 1, to effect the opening movement of the main contact 26, the latch 124 moving under the impetus of the cam 121 will effect movement of the rod 133 upwardly and in a leftwardly direction. This movement of the rod 133 causes the rocker arm 135 to pivot on pin 109 in a counterclockwise direction, thereby moving the blast valve actuating rod 136 downwardly to displace the blast valve 38 to open position. However, the crank 68 continues to pivot in a clockwise direction to effect the complete separation of the main contact 26. At this point, the cam surface 139 displaces the tongue 123 inwardly to disengage the latch 124 from the cam surface 122. Thereupon, the spring 149 operates to effect the pivotal movement ofthe rocker arm 135 in a clockwise direction about pin 109 to lift the rod 136 out of engagement with the blast valve 38. The blast valve 38 then returns to a closed position by operation of a spring 39. The spring 149 in effecting the pivotal movement of the rocker arm 135 in a clockwise direction also effects the pivotal movement of the latch 124 in a counterclockwise direction to effect a resetting of the latch 124 to its original position as depicted in FIG. 2. Thus, as the main circuit breaker contact 26 is being moved to a full open position, the blast valve 38 has been opened to supply a blast of fluid under pressure to the arcing area 42 to extinguish the are drawn between the circuit breaker contacts as they part and thereafter the blast valve 38 is automatically closed ready for immediate operation should the circuit breaker contact 26 be inadvertently returned to a closed position and then re opened as under a fault condition.

In a closing operation, the various components will be actuated from their position as depicted in FIG. 2 and schematically indicated in FIG. 4, which is the condition which is established after the main contact 26 and the resistor contact 59 are opened and the blast valve 38 closed. In a closing operation, the rod 51 will be caused to move downwardly, thereby effecting the rotation ofthe main crank 68 in a counterclockwise direction. This action will effect the pivotal movement of the toggle crank 87 in a counterclockwise direction about the pin 109 as viewed in FIG. 2. As a result, the links 88 and 91 of the two-part toggle link 86 move as a unit, upwardly effecting the pivotal movement of the bell crank 80 in a counterclockwise direction, thereby moving the resistor contact 59 to closed position, FIG. 5. During this movement of the links 88 and 91, they are maintained in a slightly over-centered in-line position by the flat spring 101 so that they act as a single rigid link As the counterclockwise pivotal movement of the crank 68 is continued to effect the closing ofthe main contact 26, the resistor contact 59 must be opened. In the preferred embodiment, the resistor contact 59 closes about six milliseconds prior to the closing of the main contact 26. Thus, with the resistor contact 59 in closed position and with the crank 68 continuing to be rotated in a counterclockwise direction, the main contact 26 will be moved to a position wherein it just makes contact with its associated stationary contact 23. Thereafter, with continued counterclockwise movement of the toggle crank 87, the long link 88 will engage a displacement means herein depicted as a positive stop 157, as depicted schematically in FIG. 6. As a result, the long link 88 is no longer capa' ble of moving with the short link 91. Thus, the two-part toggle link breaks at the toggle joint 92. With the two-part toggle link 86 broken, the spring 66 acting on the now leftwardly positioned guide piston 62 associated with the movable resistor contact 56 will operate to force the piston 62 rightwardly, as viewed in FIG. 6, to move the resistor contact 59 to open position. This action effects the pivotal movement of the bell crank 80 in a clockwise direction thereby moving the long link 88 into a vertical position; the toggle crank 87 effects the displacement of the short link 91 to a horizontal position. As this condition obtains, the main movable contact 26 will have been moved to a fully closed position, the component condition being depicted schematically in FIG. 7. With the main crank moved in a counterclockwise direction for effecting the closing of the main contact 26, the cam 121 will be moved so that the vertical cam face 122 is positioned to the right side of the tongue portion 123 of the latch 124 thereby recoupling the main crank to the blast valve operator linkage. Thus, the entire operating mechanism is reset to the position depicted in FIG. 1 and schematically indicated in FIG. 7.

Although the invention has been depicted and described in a preferred embodiment, it is to be understood that changes and modifications may be accomplished without departing from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a circuit breaker;

a main switch comprising a stationary contact and a movable contact;

a secondary switch comprising a stationary contact and a movable contact;

resilient means operably connected to bias said movable secondary contact to an open position;

mechanical drive means operably connected to operate said main switch and said secondary switch including a drive crank movable between a first and second position for effecting the operation of said switches;

a drive linkage connection between said drive crank and said secondary switch and said main switch for imparting a closing force to said secondary switch movable contact when said drive crank moves from its first position to its second position, said drive linkage being operable to release the drive force of said mechanical drive means after said drive crank has operated to effect relative movement of said secondary switch movable contact to closed position and the movement of said movable main contact to a position of engagement with the associated stationary main contact as said drive crank continues to operate to move said movable main contact to a fully engaged position with said stationary main contact; and,

yieldable means operable upon said drive linkage to maintain said linkage in operable driving condition for transmitting switch closing movement of said drive crank to said secondary switch.

2. A circuit breaker according to claim 1 wherein said drive linkage connection comprises a first link and a second link pivotally connected together, said links being operatively connected between said drive crank and said secondary switch, said links being operable when in an in-line position to transmit the closing movement of said drive crank to said secondary switch;

spring means acting on said links to yieldably maintain said first and second links in in-line position; and,

displacement means operably carried by said circuit breaker in position for engagement by said drive links to break the in-line position of said first and second links after said secondary switch has been closed and said movable main contact has just made engagement with its associated stationary main contact;

whereby said drive crank can continue to move in a contact closing operation to effect full engagement of said movable main contact with the stationary main contact and the drive connection between said drive crank and said secondary switch is interrupted, and said resilient means associated with said movable secondary contact is free to urge said movable secondary contact to open position.

3. A circuit breaker according to claim 2 wherein there is provided a stop means operably connected to prevent the breaking of said first and said second links in one direction beyond substantially an in-line position;

whereby said displacement means effects the breaking of said first and second links from an in-line position in a controlled direction.

4. A circuit breaker according to claim 3 wherein said displacement means is adjustable for orientation to a position in which displacement engagement between the displacement means and said link members can be established to effect the breaking of said first and second links from an in-line position at a particular point in the closing of said secondary switch and said main switch.

5. A circuit breaker of the fluid-blast type;

a sealed housing;

a support member carried within said housing;

a main switch comprising a hollow stationary contact and a movable contact adapted to be interengaged with said stationary contact, said main switch being operatively supported within said housing by said support member;

a secondary switch comprising a stationary contact and a movable contact engageable with said stationary contact, said secondary switch being operatively supported within said housing in electrical parallelism with said main switch by said support member;

a drive member operatively supported within said housing for movement in one direction for effecting a closing operation of said secondary switch and said main switch, said drive member being operable when moved in a second direction to effect an opening operation of said main switch without affecting the movement of said secondary switch;

a collapsible toggle linkage operably connected to said drive member and to said movable secondary switch contact in a manner that movement of said drive member in a first direction will operate to actuate said toggle linkage to effect the closing movement of said movable secondary switch contact;

a toggle crank supported for movement on said support member and operably connected to said toggle linkage to provide a controlled path of travel for said collapsible toggle linkage as it is moved to effect a closing movement of said movable secondary contact;

a movable main switch contact connecting rod operatively connected to said movable main switch contact and said drive member;

abutment means carried by said support member in position to be engaged by said toggle linkage to effeet the collapse of said toggle linkage after said movable secondary contact has been moved to a closed position so that the continued movement of said drive member in the first direction will effect complete closing engagement of said movable main contact but said drive member upon the collapse of said toggle linkage will have no force connection with said movable secondary contact to thereby free said movable secondary contact for return to an open position; and,

means operably connected to effect an opening operation of said secondary switch.

6. A circuit breaker according to claim 5 wherein said support member is of an electrical conductive material.

7. A circuit breaker of the fluid-blast type including a stationary main contact;

a movable main contact separable from said stationary contact to establish an are;

a source of fluid under pressure;

a blast valve operably connected between said source of fluid under pressure and the area where an arc is drawn between said contacts, said blast valve being normally biased to a closed position, and operable when actuated to an open position to direct a blast of fluid under pressure to the area of arcing;

operating linkage means operably connected to effect the synchronous separating movement of said movable main contact from said stationary main contact and the opening movement of said blast valve so that a blast of fluid under pressure is directed to the arcing area as said are is established between said contacts, said operating linkage means being also operable when actuated in a second direction to effect a closing movement of said movable secondary contact and thereafter the closing of said movable main contact;

releasing means actuated by said operatinglinkage means to effect a release of said blast valve after said operating linkage means has effected the disengagement of said movable main contact with its associated stationary main contact and said blast valve is thereafter biased to its normally closed position; and,

means operable on said movable secondary movable contact to urge said secondary movable contact to an open position.

8. A circuit breaker according to claim 7 wherein said operating linkage means includes cam means operable on said blast valve releasing means to actuate sid releasing means and effect the release of the operating connection between said operating linkage means and said blast valve prior to said movable main contact being moved to full open position by said operating linkage means.

9. A circuit breaker according to claim 8 wherein said blast valve releasing means comprises a latch biased into engagement with said operating linkage means and operably connected to effect the opening of said blast valve when actuated by said operating linkage means; and,

said cam means associated with said operating linkage means effects a displacement of said latch to effect an interruption in the connection between said latch and said operating linkage means to thereby free said blast valve so that it will be biased to its normally closed position.

10. A circuit breaker comprising a main switch and a secondary switch connected in parallel with said main switch, each of said switches including a stationary contact and a movable contact;

a drive means movable between a first position and a second position for actuating said main switch and said secondary switch;

biasing means associated with said secondary switch movable contact to urge said secondary switch movable contact to open position;

a source of fluid under pressure for extinguishing an are drawn between said contacts of said main switch;

a blast valve interposed between said source of fluid under pressure and the area of arcing, said blast valve being operable when actuated open to deliver a blast of fluid under pressure to the arcing area;

a first connecting means between said drive means and said main switch movable contact for effecting the closing and opening movement of said main switch movable contact when said drive means moves to its first position or its second position;

a second connecting means between said drive means and said secondary switch movable contact for effecting a closing movement of said movable secondary switch contact when said drive means moves from its first position to its second position, said second connecting means being constructed and arranged to effect a closing of said secondary switch movable contact prior to said first connecting means effecting the closing of said main switch movable contact;

a third connecting means between said drive means and said blast valve for effecting the opening of said blast valve as said drive means is moved from its second position to its first position;

releasing means operable to effect a release of said third connecting means from said drive means after said blast valve has been opened and prior to the complete opening movement of said main switch movable contact; and,

interrupting means in said second connecting means and operable to interrupt the connection to said secondary switch movable contact after the closing of said main movable contact so that said biasing means operates to return said secondary switch movable contact to an open position.

11. A circuit breaker according to claim [0 wherein said interrupting means in said second connecting means includes a pair of pivotally connected links; and,

an abutment member on the end of one of said links that has the pivotal connection with the other of said links, said abutment being constructed and arranged to engage the other of said links in a manner to establish a substantially in-line relationship between said links for transmitting the movement of said drive means to said secondary switch movable contact to effect its closing.

12. A circuit breaker according to claim 11 wherein there is provided resilient means acting on said pivotal connection of said pivotally connected links to exert a biasing force on said pivot connection to urge said links into an in-line positional relationship.

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1. In a circuit breaker; a main switch comprising a stationary contact and a movable contact; a secondary switch comprising a stationary contact and a movable contact; resilient means operably connected to bias said movable secondary contact to an open position; mechanical drive means operably connected to operate said main switch and said secondary switch including a drive crank movable between a first and second position for effecting the operation of said switches; a drive linkage connection between said drive crank and said secondary switch and said main switch for imparting a closing force to said secondary switch movable contact when said drive crank moves from its first position to its second position, said drive linkage being operable to release the drive force of said mechanical drive means after said drive crank has operated to effect relative movement of said secondary switch movable contact to closed position and the movement of said movable main contact to a position of engagement with the associated stationary main contact as said drive crank continues to operate to move said movable main contact to a fully engaged position with said stationary main contact; and, yieldable means operable upon said drive linkage to maintain said linkage in operable driving condition for transmitting switch closing movement of said drive crank to said secondary switch.
 2. A circuit breaker according to claim 1 wherein said drive linkage connection comprises a first link and a second link pivotally connected together, said links being operatively connected between said drive crank and said secondary switch, said links being operable when in an in-line position to transmit the closing movement of said drive crank to said secondary switch; spring means acting on said links to yieldably maintain said first and second links in in-line position; and, displacement means operably carried by said circuit breaker in position for engagement by said drive links to break the in-line position of said first and second links after said secondary switch has been closed and said movable main contact has just made engagement with its associated stationary main contact; whereby said drive crank can continue to move in a contact closing operation to effect full engagement of said movable main contact with the stationary main contact and the drive connection between said drive crank and said secondary switch is interrupted, and said resilient means associated with said movable secondary contact is free to urge said movable secondary contact to open position.
 3. A circuit breaker according to claim 2 wherein there is provided a stop means operably connected to prevent the breaking of said first and said second links in one direction beyond substantially an in-line position; whereby said displacement means effects the breaking of said first and second links from an in-line position in a controlled direction.
 4. A circuit breaker according to claim 3 wherein said displacement means is adjustable for orientation to a position in which displacement engagement between the displacement means and said link members can be established to effect the breaking of said first and second links from an in-line position at a particular point in the closing of said secondary switch and said main switch.
 5. A circuit breaker of the fluid-blast type; a sealed housing; a support member carried within said housing; a main switch comprising a hollow stationary contact and a movable contact adapted to be interengaged with said stationary contact, said main switch being operatively supported within said housing by said support member; a secondary switch comprising a stationary contact and a movable contact engageable with said stationary contact, said secondary switch being oPeratively supported within said housing in electrical parallelism with said main switch by said support member; a drive member operatively supported within said housing for movement in one direction for effecting a closing operation of said secondary switch and said main switch, said drive member being operable when moved in a second direction to effect an opening operation of said main switch without affecting the movement of said secondary switch; a collapsible toggle linkage operably connected to said drive member and to said movable secondary switch contact in a manner that movement of said drive member in a first direction will operate to actuate said toggle linkage to effect the closing movement of said movable secondary switch contact; a toggle crank supported for movement on said support member and operably connected to said toggle linkage to provide a controlled path of travel for said collapsible toggle linkage as it is moved to effect a closing movement of said movable secondary contact; a movable main switch contact connecting rod operatively connected to said movable main switch contact and said drive member; abutment means carried by said support member in position to be engaged by said toggle linkage to effect the collapse of said toggle linkage after said movable secondary contact has been moved to a closed position so that the continued movement of said drive member in the first direction will effect complete closing engagement of said movable main contact but said drive member upon the collapse of said toggle linkage will have no force connection with said movable secondary contact to thereby free said movable secondary contact for return to an open position; and, means operably connected to effect an opening operation of said secondary switch.
 6. A circuit breaker according to claim 5 wherein said support member is of an electrical conductive material.
 7. A circuit breaker of the fluid-blast type including a stationary main contact; a movable main contact separable from said stationary contact to establish an arc; a source of fluid under pressure; a blast valve operably connected between said source of fluid under pressure and the area where an arc is drawn between said contacts, said blast valve being normally biased to a closed position, and operable when actuated to an open position to direct a blast of fluid under pressure to the area of arcing; operating linkage means operably connected to effect the synchronous separating movement of said movable main contact from said stationary main contact and the opening movement of said blast valve so that a blast of fluid under pressure is directed to the arcing area as said arc is established between said contacts, said operating linkage means being also operable when actuated in a second direction to effect a closing movement of said movable secondary contact and thereafter the closing of said movable main contact; releasing means actuated by said operating linkage means to effect a release of said blast valve after said operating linkage means has effected the disengagement of said movable main contact with its associated stationary main contact and said blast valve is thereafter biased to its normally closed position; and, means operable on said movable secondary movable contact to urge said secondary movable contact to an open position.
 8. A circuit breaker according to claim 7 wherein said operating linkage means includes cam means operable on said blast valve releasing means to actuate sid releasing means and effect the release of the operating connection between said operating linkage means and said blast valve prior to said movable main contact being moved to full open position by said operating linkage means.
 9. A circuit breaker according to claim 8 wherein said blast valve releasing means comprises a latch biased into engagement with said operating linkage means and operably connected to effect the opening of said blast valve when actUated by said operating linkage means; and, said cam means associated with said operating linkage means effects a displacement of said latch to effect an interruption in the connection between said latch and said operating linkage means to thereby free said blast valve so that it will be biased to its normally closed position.
 10. A circuit breaker comprising a main switch and a secondary switch connected in parallel with said main switch, each of said switches including a stationary contact and a movable contact; a drive means movable between a first position and a second position for actuating said main switch and said secondary switch; biasing means associated with said secondary switch movable contact to urge said secondary switch movable contact to open position; a source of fluid under pressure for extinguishing an arc drawn between said contacts of said main switch; a blast valve interposed between said source of fluid under pressure and the area of arcing, said blast valve being operable when actuated open to deliver a blast of fluid under pressure to the arcing area; a first connecting means between said drive means and said main switch movable contact for effecting the closing and opening movement of said main switch movable contact when said drive means moves to its first position or its second position; a second connecting means between said drive means and said secondary switch movable contact for effecting a closing movement of said movable secondary switch contact when said drive means moves from its first position to its second position, said second connecting means being constructed and arranged to effect a closing of said secondary switch movable contact prior to said first connecting means effecting the closing of said main switch movable contact; a third connecting means between said drive means and said blast valve for effecting the opening of said blast valve as said drive means is moved from its second position to its first position; releasing means operable to effect a release of said third connecting means from said drive means after said blast valve has been opened and prior to the complete opening movement of said main switch movable contact; and, interrupting means in said second connecting means and operable to interrupt the connection to said secondary switch movable contact after the closing of said main movable contact so that said biasing means operates to return said secondary switch movable contact to an open position.
 11. A circuit breaker according to claim 10 wherein said interrupting means in said second connecting means includes a pair of pivotally connected links; and, an abutment member on the end of one of said links that has the pivotal connection with the other of said links, said abutment being constructed and arranged to engage the other of said links in a manner to establish a substantially in-line relationship between said links for transmitting the movement of said drive means to said secondary switch movable contact to effect its closing.
 12. A circuit breaker according to claim 11 wherein there is provided resilient means acting on said pivotal connection of said pivotally connected links to exert a biasing force on said pivot connection to urge said links into an in-line positional relationship. 